Technical Field
The invention relates to a dual mode serial transmission apparatus and a method for switching mode thereof.
Related Art
In a serial transmission system constructed through a complementary metal oxide semiconductor (CMOS) manufacturing process, a commonly used mode of a transmitting end includes a low voltage differential signal transmission mode (LVDS) and a current mode logic (CML). Referring to FIG. 1A and FIG. 1B, FIG. 1A and FIG. 1B are circuit diagrams of a LVDS mode serial transmission apparatus and a CML mode serial transmission apparatus. In FIG. 1A, the LVDS mode serial transmission apparatus 110 is composed of current sources IS1, IS2, switches S1-S4 and a resistor R1. In FIG. 1B, the CML mode serial transmission apparatus 120 is composed of switches S5, S6, a current source IS3 and resistors R2 and R3, and the CML mode serial transmission apparatus 120 provides paths for pulling up to an operating power VCC. The serial transmission apparatuses 110 and 120 generate complementary output signals OUTP and OUTN through switching operations of the switches thereof.
Regardless of the LVDS mode or the CML mode serial transmission apparatus, due to non-ideal of control signals used for controlling the switches S1-S6, a period of a temporary transition state when the switches S1-S7 being switched between logic 1 and logic 0 in response to the control signals, and the temporary transition state is generally a main reason for producing a common mode noise, such that the whole system is interfered by electromagnetic interference.